This disclosure relates to an engine control system used during cold start of a Gasoline Direct-Injection Compression-Ignition (GDCI) engine.
Operation of a GDCI engine can be challenging due to the kinetically driven nature of the combustion process. Initiating autoignition requires sufficient operating pressure and temperature within the combustion chamber. Although the intake manifold in some GDCI engines utilize electric heaters to more rapidly heat the intake air (and thus raise combustion chamber temperatures), the engine still may suffer from poor combustion efficiency and high emissions until the engine reaches operating temperatures.
Catalysts are commonly used in an engine's exhaust gas path to reduce emissions substantially at significant distances from the combustion chamber. For example, electrically heated catalysts have been used substantially downstream from the engines' exhaust manifolds to shorten catalyst “light-off” time to improve emissions when the engine is cold.
Some engines use internal exhaust gas recirculation (EGR), or “rebreath,” to reduce emissions once the engine has reached operating temperatures. During rebreath the exhaust valves are opened during the intake stroke to allow some exhaust gases in the exhaust gas path to enter the combustion chamber through the exhaust port in the cylinder head. Rebreathing exhaust gases during cold start, however, has not been useful and is not employed.